title: Identification and characterization of a novel fibril forming peptide in fungal starch binding domain.
abstract: Scanty information is available regarding the chemical basis for structural alterations of the carbohydrate-binding modules (CBMs). The N-terminal starch binding domain (SBD) of Rhizopus oryzae glucoamylase (GA) forms fibrils under thermal stress, presenting an unusual conformational change from immunoglobulin-like to beta-sheet-rich structure. Site-directed mutagenesis revealed that the C-terminal Lys of SBD played a crucial role in the fibril formation. The synthetic peptide (DNNNSANYQVSTSK) representing the C-terminal 14 amino acid residues of SBD was further demonstrated to act as a fibril-forming segment, in which terminal charges and an internal NNNxxNYQ motif were key fibril-forming determinants. The formation of fibril structure in a fungal SBD, caused by its chemical and biophysical requirements, was demonstrated for the first time.
authors.affiliation: Institute of Molecular and Cellular Biology and Department of Life Sciences, National Tsing Hua University, No. 101, Section 2, Kuang Fu Road, Hsinchu 300, Taiwan, ROC.
authors.forename: Wei-Ting
authors.initials: WT
authors.lastname: Liu
authors.forename: Shu-Chuan
authors.initials: SC
authors.lastname: Lin
authors.forename: Wei-I
authors.initials: WI
authors.lastname: Chou
authors.forename: Tseng-Huang
authors.initials: TH
authors.lastname: Liu
authors.forename: Rong-Long
authors.initials: RL
authors.lastname: Pan
authors.forename: Der-Lii
authors.initials: DL
authors.lastname: Tzou
authors.forename: Tzu-En
authors.initials: TE
authors.lastname: Hua
authors.forename: Margaret Dah-Tsyr
authors.initials: MD
authors.lastname: Chang
mesh_terms: D000409:Alanine / Q000235:genetics / Q000378:metabolism; D000595:Amino Acid Sequence; D000682:Amyloid / Q000096:biosynthesis*; D005656:Fungal Proteins / Q000235:genetics / Q000378:metabolism* / Q000648:ultrastructure; D005087:Glucan 1,4-alpha-Glucosidase / Q000235:genetics / Q000378:metabolism* / Q000648:ultrastructure; D006358:Hot Temperature; D008969:Molecular Sequence Data; D016296:Mutagenesis; D010455:Peptides / Q000737:chemistry / Q000235:genetics / Q000378:metabolism; D017434:Protein Structure, Tertiary / Q000235:genetics; D012233:Rhizopus / Q000201:enzymology*; D013213:Starch / Q000378:metabolism*
chemical_list: D000682:Amyloid; D005656:Fungal Proteins; D010455:Peptides; D013213:Starch; D005087:Glucan 1,4-alpha-Glucosidase; D000409:Alanine